1. Field of the Invention
The present invention relates to a reciprocating compressor, and more particularly, to a reciprocating compressor configured to reduce a fabrication cost by simplifying a supply structure of lubricating oil.
2. Description of the Conventional Art
Generally, compressors are classified as a rotary compressor, a reciprocating compressor, a scroll compressor, and etc. according to a compression method of a fluid.
FIG. 1 is a sectional view showing a reciprocating compressor in accordance with the conventional art.
The conventional reciprocating compressor comprises: a hermetically sealed case 106 to which a suction pipe 102 and a discharge pipe 104 are connected; a reciprocating motor 108 disposed in the case 106 for generating a reciprocation force; a compressing unit 110 for compressing a fluid by receiving the reciprocation force generated by the reciprocating motor 108 and a lubricating unit 112 for supplying lubricating oil to each frictional generating part of the compressor; and etc.
The reciprocating motor 108 includes: an outer stator 118 of a cylindrical shape fixed between a second frame 114 and a third frame 116; an inner stator 120 disposed at an inner circumferential surface of the outer stator 118 and spaced therefrom by a certain air gap; a winding coil 122 disposed inside the outer stator 118 and to which an external power is applied; and a magnet 124 disposed between the outer stator 118 and the inner stator 120 and linearly reciprocating when power is applied to the winding coil 122.
The magnet 124 is fixed to an outer circumferential surface of a magnet holder 126, and the magnet holder 126 is connected to a piston 128 of the compressing unit 110. The piston 128 is connected to a spring supporter 130.
A first resonant spring 134 and a second resonant spring 136 are respectively disposed between one side surface of the spring supporter 130 and the first frame 132 and between another side surface of the spring supporter 130 and the second frame 114, thereby inducing a resonant movement of the piston 128.
The compressing unit 110 includes the piston 128 connected to the magnet holder 126 and linearly reciprocated; a cylinder 142 within which the piston 128 is slidably inserted, forming a compression chamber 140, and fixed to the first frame 132; a suction valve 146 mounted at the front side of the piston 128 for opening and closing an inlet 144 formed in the piston 128; and a discharge valve assembly 148 mounted at the front side of the cylinder 142 for discharging a compressed fluid externally when a pressure inside the compression chamber 140 is more than a preset pressure.
The discharge valve assembly 148 includes: a discharge valve 150 mounted to the front side surface of the cylinder 142 for discharging a compressed fluid; a discharge cover 154 mounted at the front side of the cylinder 142 and to which a discharge pipe 152 for discharging a fluid is connected; and a spring 156 disposed between the inner side surface of the discharge cover 154 and the discharge valve 150 for elastically supporting the discharge valve 150.
A first supporting spring 158 is disposed between the third frame 116 and the upper surface of the case 106, and a second supporting spring 160 is disposed between the discharge cover 154 and the lower surface of the case 106.
As shown in FIG. 2, the lubricating unit is provided for supplying lubricating oil contained at the lower portion of the case 106 to sliding surfaces between the cylinder 142 and the piston 128. The lubricating unit includes: a pumping unit 162 fixed at one side of the first frame 132, for pumping lubricating oil by using vibration generated at the time of driving the compressor; an opening/closing valve 164 for opening and closing a passage for the lubricating oil pumped by the pumping unit 162; and a lubricating oil passage 166 formed at the first frame 132 for supplying lubricating oil to the sliding surfaces between the cylinder 142 and the piston 128.
The pumping unit 162 includes: a lubricating cylinder 168 fixed at one side of the first frame 132; a lubricating piston 170 linear-movably disposed in the lubricating cylinder 168 and reciprocated by vibration of the compressor, for pumping lubricating oil; two springs 172 for elastically supporting the opposite sides of the lubricating piston 170; and a suction pipe 174 for sucking lubricating oil contained in the lower portion of the case 106.
The opening/closing valve 164 is disposed between the front side of the cylinder 142 and the lubricating oil passage 166 to thus suck lubricating oil into the suction pipe 174 in accordance with a reciprocation of the piston 170 and to supply the sucked lubricating oil to the lubricating oil passage 166.
The lubricating unit of the conventional compressor will now be explained. The lubricating piston 170 is reciprocated inside the lubricating cylinder 168 by a vibration generated when the compressor is driven. By a pressure generated by the reciprocation of the lubricating piston 170, lubricating oil is sucked through the suction pipe 174.
The lubricating oil sucked into the suction pipe 174 is compressed by an open/close operation of the opening/closing valve 164 thus to be supplied to the frictional surfaces between the cylinder 142 and the piston 128 through the lubricating oil passage 166.
However, since the lubricating unit of the conventional reciprocating compressor includes a plurality of components such as the pumping unit for pumping lubricating oil, the opening/closing valve for opening and closing a passage of lubricating oil pumped by the pumping unit, and etc., the structure is complicated. According to this, the entire structure of the compressor becomes complicated and a fabrication cost is increased.
Also, the pumping unit is not driven when the compressor is stopped, so that lubricating oil is collected into the lower portion of the case. According to this, there is insufficient lubricating oil at the frictional surfaces between the cylinder and the piston during an initial driving of the compressor, thereby resulting in abrasion at the frictional surfaces.